Introduction of the trigger system and the measurement of the trigger efficiency for the L3 + Cosmics experiment

The trigger process of L3+Cosmics experiment at CERN is introduced briefly. Also we checked whether the settings of the L3+Cosmics trigger system by simulation are correct or not and introduced a method for trigger efficiency calculation. To get the trigger efficiency for the mu spectrum measurement, an experimental data sample, which includes events passing the trigger set to measure the mu spectrum, not passing, is needed. Then L3+C trigger process is simulated with these events in this sample to know how many events should pass the trigger. By checking a trigger bit recorded in the experimental data, one can know how many events passed the trigger in hardware in these simulated events. The ratio then determines the trigger efficiency for mu spectrum measurement, and the systematic error is analyzed. The results on trigger efficiency have been used in measurement of the mu spectrum. (8 refs).